Answered By: General Reference Last Updated: Feb 01, 2017 Views: 148
Fell is a Middle English word meaning cruel.
“One fell swoop” is from a line in Act IV, Scene III, lines 217-20 of Macbeth where one fell swoop refers metaphorically to a bird of prey’s sudden, cruel strike:
He has no children. All my pretty ones?
Did you say all? O hell-kite! All?
What, all my pretty chickens and their dam
At one fell swoop”
Shakespeare, William. Macbeth, Bantam Books: Westminster, MD, 1988. p 245.
The Oxford English Dictionary defines the adjective fell as “Of animals and men, their actions and attributes: Fierce, savage; cruel, ruthless; dreadful, terrible.”
“Fell,” Oxford English Dictionary [online version]. Oxford: Oxford University Press, 2011.
The expression “In one fell swoop” is used today to mean “in a single time; at once.”
Sera, Lucia. Boatload of Idioms : Over a Thousand English Expressions, Waterbury, CT, USA: Vocalis, Limited, 2004. p 165.